From e6111686d731af1e621ea9f38babef50610f7717 Mon Sep 17 00:00:00 2001
From: Kirill Isakov <bootctl@gmail.com>
Date: Sun, 1 May 2022 23:09:06 +0600
Subject: [PATCH] Replace getrandom() with getentropy()

Unlike getrandom(), this function is supported by most BSDs
(with the exception of NetBSD), and by various Illumos distributions.
---
 src/linux/meson.build          |  6 +-----
 src/meson.build                |  2 ++
 src/random.c                   | 11 ++++++-----
 test/unit/test_random_noinit.c |  4 ++--
 4 files changed, 11 insertions(+), 12 deletions(-)

diff --git a/src/linux/meson.build b/src/linux/meson.build
index 0213d060..8c0f1377 100644
--- a/src/linux/meson.build
+++ b/src/linux/meson.build
@@ -2,13 +2,9 @@ check_headers += [
   'linux/if_tun.h',
   'netpacket/packet.h',
   'sys/epoll.h',
-  'sys/random.h',
 ]
 
-check_functions += [
-  'recvmmsg',
-  'getrandom',
-]
+check_functions += 'recvmmsg'
 
 src_tincd += files('device.c')
 
diff --git a/src/meson.build b/src/meson.build
index 351124e7..02a42833 100644
--- a/src/meson.build
+++ b/src/meson.build
@@ -62,6 +62,7 @@ check_headers = [
   'sys/ioctl.h',
   'sys/mman.h',
   'sys/param.h',
+  'sys/random.h',
   'sys/resource.h',
   'sys/socket.h',
   'sys/stat.h',
@@ -85,6 +86,7 @@ check_functions = [
   'explicit_bzero',
   'explicit_memset',
   'fchmod',
+  'getentropy',
   'gettimeofday',
   'memset_s',
   'mlockall',
diff --git a/src/random.c b/src/random.c
index fad7173f..f2e898f7 100644
--- a/src/random.c
+++ b/src/random.c
@@ -2,12 +2,12 @@
 
 #include "random.h"
 
-#ifndef HAVE_GETRANDOM
+#ifndef HAVE_GETENTROPY
 static int random_fd = -1;
 #endif
 
 void random_init(void) {
-#ifndef HAVE_GETRANDOM
+#ifndef HAVE_GETENTROPY
 	random_fd = open("/dev/urandom", O_RDONLY);
 
 	if(random_fd < 0) {
@@ -23,7 +23,7 @@ void random_init(void) {
 }
 
 void random_exit(void) {
-#ifndef HAVE_GETRANDOM
+#ifndef HAVE_GETENTROPY
 	close(random_fd);
 #endif
 }
@@ -32,8 +32,9 @@ void randomize(void *vout, size_t outlen) {
 	uint8_t *out = vout;
 
 	while(outlen) {
-#ifdef HAVE_GETRANDOM
-		ssize_t len = getrandom(out, outlen, 0);
+#ifdef HAVE_GETENTROPY
+		int reqlen = (int) MIN(256, outlen);
+		int len = !getentropy(out, reqlen) ? reqlen : -1;
 #else
 		ssize_t len = read(random_fd, out, outlen);
 #endif
diff --git a/test/unit/test_random_noinit.c b/test/unit/test_random_noinit.c
index aeedda95..fa6087f1 100644
--- a/test/unit/test_random_noinit.c
+++ b/test/unit/test_random_noinit.c
@@ -2,7 +2,7 @@
 
 #include "unittest.h"
 
-#ifdef HAVE_GETRANDOM
+#ifdef HAVE_GETENTROPY
 int main(void) {
 	return 1;
 }
@@ -14,4 +14,4 @@ int main(void) {
 	randomize(buf, sizeof(buf));
 	return 0;
 }
-#endif // HAVE_GETRANDOM
+#endif // HAVE_GETENTROPY
-- 
2.20.1